1. Field of the Invention
This invention relates to the dyeing with disperse dyes of synthetic hydrophobic textile materials to obtain deep shades.
2. Description of the Prior Art
Bostock et al. disclose in U.S. Pat. Nos. 4,153,413 and 4,147,510 the dyeing of polyester or mixed polyester and cellulosic blends utilizing a disperse dyestuff or mixture of a disperse and reactive dyestuff to obtain improved fastness properties. Certain disperse azo dyestuffs free from carboxylic acid and sulfonic acid groups are utilized. The process includes fixing the dyed textile material at elevated temperatures and then subjecting the dyed textile material to an aqueous alkaline treatment at a pH above 8 and at a temperature between 50.degree. and 85.degree. C. The processes of Bostock et al are said to provide excellent fastness to wet treatments, however, there is no indication that the wet treatments contemplated include exposure to organic solvents.
Fishwick et al. in U.S. Pat. No. 3,993,438 disclose the dyeing of mixed polyester and cellulosic blended textile materials using mixtures of disperse and reactive dyestuffs. The process steps are similar to those disclosed in the Bostock et al references cited above. Excellent fastness to wet treatments is said to characterize the dyed textile materials produced by the process of Fishwick et al.
It is known to color synthetic hydrophobic textile materials, particularly aromatic polyester materials with disperse dyestuffs utilizing an aqueous dispersion thereof which is applied to the textile material by an exhaustion dyeing, padding, or printing process. The dyestuff is thereafter fixed by a subsequent heat treatment of the dyed textile material. In order that the resulting colored textile material will have the maximum fastness properties, it is usually necessary that any unfixed dyestuff be thereafter removed from the surfaces of the fibers of the textile material. This is usually achieved by the so-called "reduction clear" treatment involving the treatment of the dyed and heat-treated textile material with a warm aqueous alkaline solution of sodium hydrosulfite.